1. Field of the Invention
The present invention relates to an inserting device for inserting a deformable intraocular lens into the eye in place of the natural lens when the latter is physically extracted because of cataracts, and particularly to an inserting device for a deformable intraocular lens which has an improved holder member for holding the deformable intraocular lens.
2. Description of the Related Art
It is generally accepted that when a cataract-impaired lens is surgically extracted, smaller incisions in the eyeball cause less chance of postoperative astigmatism.
Accordingly, a technique called KPE (Kelman's pharmacoemulsification; suction of lens substance crushed by ultrasonic emulsification) using an ultrasonic emulsification/suction apparatus has been developed. With this apparatus, an opaqued lens is crushed and emulsified by ultrasonication, and then sucked for removal. This technique permits an operation in which lenses are extracted through a small incision of approximately 4 mm, as compared to larger incisions of about 10 mm according to the conventional ECCE operation technique (extracapsular cataract extraction).
In connection with the technique which made small incisions possible as mentioned above, intraocular lenses which can be inserted through a small incision have been developed. Conventional intraocular lenses have an optical part made of a hard material such as glass or plastic, and therefore, the incisions prepared at the time of transplant are greater than the diameter of the optical part which are in most cases 6.5 mm or more. Accordingly, even though a lens is extracted through a small incision according to the KPE technique, it is necessary that the incision be enlarged when a hard intraocular lens is inserted.
To solve this problem, Japanese Patent Application No. 558-18005 (Japanese Patent Application Laid-open (kokai) No. 146346/1983 , Japanese Patent Publication No. H5-58748) discloses a deformable intraocular lens which can be inserted through a small incision made in an eyeball.
As shown in FIG. 4 (Prior Art), such an intraocular lens 1 is composed of an optical part 2 made of an elastic material and having predetermined memory characteristics, and two symmetrically disposed supports 3 which hold the optical part within the eye. The supports 3 are made of a different material from the optical part 2, and the bases 3a of the supports 3 are embedded in the peripheral portion of the optical part 2 for fixing, while the wire-shaped tails 3b are curved.
The supports 3 are made of a material such as a synthetic resin having a sufficient hardness and the wire-shaped tails 3b extending from the optical part 2 have a spring function so that the optical part 2 is stably placed in the eye on the optical axis even when the lens 1 receives force such as compression stress within the eye.
An inserting device for deformable intraocular lenses has been proposed as described in Japanese Patent Application No. H3-142067 Japanese Patent Application Laid open (kokai) No. H5-103803). As shown in FIG. 5 and FIG. 6, the inserting device is composed of a cylindrical body 4 provided with a receiving opening 4a having a narrowed portion at its forward end portion; a pusher mechanism 7 provided with a pusher rod 5 inserted into the body 4, and a male-screw sleeve 6 which is screw-engaged with a female screw of the body 4 for advancing and retracting the pusher rod 5; and a holder member 11 provided with a lens holding section 9 having an opening/closing mechanism 8, and a tubular insertion tip 10 formed at the front side of the lens holding section 9.
In the lens holding section 9, a stationary half sleeve 12 is integrally formed with the rear end of the insertion tip 10, and a movable half sleeve 13 facing the stationary half sleeve 12 is provided near the rear end of the insertion tip 10. The lower edge of the movable half sleeve 13 is joined with the stationary half sleeve 12 through an unillustrated hinge for opening and closing operations. Stationary and movable pressing flanges 15 and 16 are projected from the upper edges of the stationary and movable half sleeves 12 and 13.
When the opening/closing mechanism 8 composed of the movable half sleeve 13, the hinge portion and the movable pressing flange 16 is closed, the movable pressing flange 16 contacts the stationary plate 15 so that the movable half sleeve 13 contacts the stationary half sleeve 12, thereby forming a tubular shape which is aligned with the insertion tip 10.
When the deformable intraocular lens 1 is inserted into the eye in place of the natural lens using the above-described conventional inserting device, the holder member 11 is taken out from the body 4 and the opening/closing mechanism 8 is then opened. The intraocular lens 1 is placed on the lens holding section 9 of the holder member 11. Subsequently, the opening/closing mechanism 8 is closed so that the intraocular lens 1 is deformed into a smaller shape. While maintaining this state, a major part of the holder member 11 excepting the pressing flanges 15 and 16 is inserted into the front portion of the body 4 through the receiving opening 4a so that the pressing flanges 15 and 16 are projected upward from the receiving opening 4a.
The holder member 11 is subsequently advanced to insert the pressing flanges 15 and 16 into the narrowed portion of the receiving opening 4a so that the opening/closing mechanism 8 is maintained closed, and the insertion tip 10 is projected from the forward end of the body 4. In this way, the assembly of the inserting device is carried out.
After the assembly of the inserting device, the insertion tip 10 of the holder member 11 is inserted into the eye through a small incision of about 4 mm formed in the eye ball. A cylindrical operation sleeve 6a formed at the rear end of the male-screw sleeve 6 of the pusher mechanism 7 is then rotated to advance the pusher rod 5 from its retracted position. With this operation, the forward end of the pusher rod 5 contacts the intraocular lens 1 to push out the intraocular lens 1 from the lens holding section 9 of the holder member 11 through the insertion tip 10 so that the intraocular lens 1 is inserted into the eye through the small incision. The optical part 2 of the intraocular lens 1 is restored from the small deformed shape to the original large shape according to the shape memorizing characteristics of the lens. As described above, the insertion of an intraocular lens through a small incision is realized by the improvements in both the intraocular lens and the insertion apparatus.
In the conventional insertion apparatus, the body 4, the pusher rod 5 of the pusher mechanism 7 and the male-screw sleeve 6 are made of a metallic material, and the holder member 11 is integrally made of a flexible synthetic resin.
In the conventional inserting device for intraocular lenses, when the pusher rod is advanced by an operation of the pusher mechanism while an intraocular lens has been deformed in a smaller shape and held by the lens holding section of the holder member, the pusher rod interferes with a support extending from the rear side (the side corresponding to the rear end of the holder member) of the optical portion of the intraocular lens at the beginning of the push-out operation, so that the support receives external force directly form the pusher rod. Since the support is made of a hard material having a spring function as described above, the support has a chance to be permanently deformed, thereby causing a problem that the optical part cannot be supported at a predetermined position within the eye, and the original function of the support deteriorates.
Therefore, as shown in FIG. 6, the pusher rod 5 is provided at its forward end with a push-out portion 5a whose upper and lower portions are cut away so as to prevent the pusher rod 5 from interfering with the support 3 of the intraocular lens 1. However, in the case where the intraocular lens 1 is incorrectly held in the holder member 11, for example, the position of the intraocular lens 1 deviates from the desired position, the push-out portion 5a interferes with the support 3.